Method and apparatus for turning workpieces

ABSTRACT

Disclosed here are methods and automatic apparatus for grinding cylindrical workpieces, such as the contoured rolls used in metal rolling mills. The methods and apparatus involve (1) automatic finding of the lengthwise center of rolls of different and undetermined lengths so as to establish a reference position for the execution of a numerically programmed path defined relative to the center of a roll as a point of symmetry, (2) the storage of the successive instructions of multi-axis movements making up a numerically defined profile or contoured path, and the use of those instructions repeatedly and in whole or in part as called for by different ones of a sequence of commands read from storage and executed in succession, (3) the automatic alignment of the roll axis parallel to the longitudinal axis of motion in a grinding machine by pivoting of one end of the roll about the other until the sensed difference in positions of the roll surface, along an axis transverse to the longitudinal axis and at locations near opposite ends of the roll, is changed to a predetermined fraction of the originally sensed difference, (4) the initiation of grinding passes from that end of a roll which is largest in diameter, so as to avoid &#39;&#39;&#39;&#39;digging in&#39;&#39;&#39;&#39; or increasing the depth of wheel bite as the wheel moves lengthwise of the roll, (5) the execution of continuous passes of the grinding wheel with pre-programmed values of feed rate, wheel speed, roll speed, continuous infeed and incremental infeed until a pre-programmed thickness of material has been removed from the roll surface, and (6) the grinding down of a roll until it is reduced to a diameter equal that of a previously ground roll of a matched pair. These functions are all obtained by the calling out and execution of pre-established routines in response to the reading from storage of pre-programmed sequence commands, so that in the disclosed method and apparatus there is an automatic progression from each type of operation to the next, and with the following of numerically defined profile whenever it is required.

United States Patent Clark, Jr.

[54] METHOD AND APPARATUS FOR TURNING WORKPIECES Stephen C. Clark, Jr., Phoenixville, Pa.

The lngersoll Milling Machine Company, Rockford, Ill.

[22] Filed: Jan.25, 1971 [21] Appl.No.: 109,523

[72] Inventor:

[73] Assignee:

Related US. Application Data [62] Division of Ser. No. 790,323, Jan. 10, 1969.

[52] U.S.Cl. ..51/165 TP, 5l/49,5l/289R [51] Int. Cl ..B24b 5/04 [58] Field of Search ..51/49, 165 R, 165 TP, 165.71,

5l/l65.74 165.75, 165.76, 165.77, 289 R, 326, 327', 82/14 B, 14 D, 21 B [56] References Cited Primary Examiner- Lester M. Swingle Attorney-Wolfe, Hubbard, Leydig, Voit & Osann 57 ABSTRACT Disclosed here are methods and automatic apparatus forgrinding cylindrical workpieces, such as the contoured rolls used in metal rolling mills. The methods and apparatus involve l) automatic finding of the lengthwise center of rolls of different and undetermined lengths so as to establish a reference position for the execution of a numerically programmed path defined relative to the center of a roll as a point of symmetry, (2) the storage of the successive instructions of multi-axis movements making up a numerically defined profile or contoured path, and the use of those instructions repeatedly and in whole or in part as called for by different ones of a sequence of commands read from storage andexecuted in succession, (3) the automatic alignment of the roll axis parallel to the longitudinal axis of motion in a grinding machine by pivoting of one end of the roll about the other until the sensed difference in positions of the roll surface, along an axis transverse to the longitudinal axis and at locations near opposite ends of the roll, is changed to a predetermined fraction of the originally sensed difference, (4) the initiation of grinding passes from that end of a roll which is largest in diameter, so as to avoid digging in or increasing the depth of wheel bite as the wheel moves lengthwise of the roll, (5) the execution of continuous passes of the grinding wheel with pre-programmed values of feed rate, wheel speed, roll speed, continuous infeed and incremental infeed until a pre-programmed thickness of material has been removed from the roll surface, and (6) the grinding down of a roll until it is reduced to a diameter equal that of a previously ground roll of a matched pair. These functions are all obtained by the calling out and execution of preestablished routines in response to the reading from storage of pre-programmed sequence commands, so that in the disclosed method and apparatus there is an automatic progression from each type of operation to the next, and with the following of numerically defined profile whenever it is required.

6 Claims, 27 Drawing Figures PATENTEDMAY 91972 3560847 SHEET nanr 18 8 -89 PSL 8 5 PSR A a 4 I I i W 25 Stephen. C. C/arACJn.

a, 42% WVJ/ M PATENTEDMAY 9 m2 SHEET O a 0F 18 k MW Tc we w a PATENTEDMAY 91972 3.660.947

SHEET 08 0F 18 K H SIGNAL Ui-rom {r m 06 IN 33.0000 FIGB :16. IO

4} K189 J5 ARV PRESET GATE5 2 PRESET GAIES (:H PRESET GATES] \IBQ- u (i ERE TI N 331 u ESIDIRECTIONAL SENSOR A J1 g N EQ ZERO TO FIG (5F Q H 252 Q) READOUT cmzs QET E/QEE o 15 ll L190 IN FIGJO I85 N fi/ OUT DIRECTION -u BIDHZECHONAL @C: SENSER A J1 PULSEK D? COUNTEK mvcm-ro r PATENTEDMM 9|972 3,660,947

SHEET 13m 18 L 5 Ll d-rw'o RMLY/ TABLE OF CONTENTS Column Abstract of the disclosure P Cross-reference to a related application 1 Background of the invention 1 Summary of the invention.l... 2 Brief description of the drawings 2 Description of preferred embodiments 3 A. An exemplary machine tool 3 B. Control instrumentalities on the grinding machine.. 6 1. Feedback pulse generators 6 p 2. Steadyrest servomotor 3. Sensing switches 5 4. Probe assemblies 7 5. Proximity switches 9 C. The coutlol system in 9 1. Contouring apparatus 9 2. Sequence command system 12 3. Data manipulation apparatus 13 1). Methods and apparatus for grinding a 011 15 1. Setup procedure 15 2. Location of lengthwise center; M61 7 (a) Movement of the swivel base to the center of B travel 17 (1)) Setting the platform 35 to the center oiX axis travel. [8 (c) Mp vement of proximity switches to operative posi- 1.8 ions ((1) Movement of wheel to center of roll l9 3. Automatic alignment of the roll axis 23 (a) Startup operations 23 Movement to location of first gaging band 25 (e) llriiliiring the wheel into touching contact with the re 2 (d) Grinding right gage band to predetermined depth.. 27 (e) Movement of wheel to location of left gage band... 28 (i) Grinding of the left gaging baud 29 (g) Retraction of the wheel free of the roll 29 (h) Sensing the location of the left gaging band on the v rear side of the roll 30 4. Determining direction of first g1 in (a) Right end larger. 37 (b) Left end larger 38 Status of the system prior to first grinding pass. 38 (d) First grinding pass and continuous passing.. 39 (i) Case I-Matenel removal incomplete. 40 (ii) Case lIMaterial removal complete. 4i 6. Rough grinding 42 6. Finish grinding r 43 7.. Sensing and signaling the roll diameter 44 8. Cleaning up the roll surface by sparking passes 9 a. Polishing passes 5| E. Grinding a second roll to the same diameter 52 31.41 ere-nee21 19942 1e--7 CROSS-REFERENCE TO A RELATED APPLICATION BACKGROUND OF THE INVENTION The present invention relates in general to methods and apparatus for the turning of cylindrical workpieces, and while it will find advantageous use in the operation of lathes, the invention is adapted to be applied with special advantages in the operation of grinding machines for shaping or renewing the shape of rolls such as those employed in metal rolling mills.

in the operation of large installations for the rolling of steel or aluminum into thin sheets or strips for coiling, the high inter-roll pressures and roll speeds result in severe wear of the surfaces of the individual rolls. The wear is often non-uniform, and any roll surface irregularities result in magnified surface imperfections in the sheets or strips. it is common practice to change the rolls in a given mill stand frequency, as often as once per 8 hour shift. When each worn roll is removed from the mill, there is a need to have its surface re-finished or reground to nearly perfect smoothness and with the desired cylindrical shape (which may be a convex or concave contour lengthwise of the roll to compensate for roll loading pressure and produce a desired cross sectional shape in the rolled strip). To keep a large mill, and the investment which it represents, operating efficiently, it is desirable to re-grind worn rolls not only quickly so that they may be returned to service, but also with precision.

To grind any roll to a desired profile, the roll must be supported by the grinding machine with the axis of the roll parallel to the longitudinal path of travel followed by the grinding wheel as it moves along the roll. Unless the roll axis is made parallel with the longitudinal path, the roll will be formed with an undesired shape after grinding has been completed.

in many cases after a roll with a given profile has been aligned with its axis parallel to the longitudinal path, neither its front side nor its rear side will be parallel to the path but instead will be skewed relative to the path. As a result, the diameter of the roll near one end of the path will be larger than that near the other end. If the initial pass of the grinding wheel is from the small and of the roll toward the larger end, the grinding wheel would take a progressively deeper bite as it moves along the roll and this could result in damage to the wheel if the latter should gouge into the large end of the roll.

SUMMARY OF THE INVENTION The principal object of the present invention is to provide a new and advantageous method and apparatus by which at least the initial pass of a turning tool along a cylindrical workpiece is always effectcd by movement of the tool from the larger end of the workpiece toward the smaller end,so that the depth of bite of the tool becomes progressively smaller to avoid gouging of the tool into the workpiece.

A further object is to provide a new and improved method and apparatus for aligning the axis of the workpiece parallel with the path of longitudinal movement of the turning tool. More specifically, it is an object to adjust the position of one end of a cylindrical workpiece in a direction transverse to the longitudinal motion of a tool, by utilizing the same sensor which initially detects misalignment, to sense and signal when the necessary corrective adjustment has been completed. A related object is to obtain quickly and preferably automatically the complete operation of sensing misalignment of a workpiece axis and adjusting the workpiece in a turning machine to align the workpiece axis, irrespective of whether the workpiece is initially cylindrical or tapered, i.e., has equal or unequal diameters at'its opposite ends; and to use the signals produced during such sensing to determine and control the end of the workpiece from which the initial machining pass is begun.

Another important objective of the invention is to further utilize the same sensor which signals misalignment of the workpiece for also signaling the comparative diameters of the ends of the workpiece, the latter signals being used to effect the initial pass of the turning tool from the larger end of the workpiece toward the smaller end thereof.

The foregoing summary of the invention and the advantageous objectives achieved thereby will be better understood after consideration of the more detailed description of a specific, exemplary embodiment of the methods and apparatus. And additional'advantages will also become apparent as the detailed description proceeds with reference to the accompanying drawings. While the invention has been shown and willbe described in'some detail with reference to specific and exemplary procedures, and with reference to particular embodiments of the apparatus, there is no intention to limit the invention to such details. On the contrary, it is intended here to cover all alternatives, modifications and equivalents which fall within the spirit and scope of the invention as expressed in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS In the attached drawings:

FIG. 1 is a fragmentary plan view, partly in diagrammatic form, of an exemplary grinding machine;

FIG. 2 is a vertical section taken substantially along the offset line 2-2 ofFIG. l;

FIG. 3 is a diagrammatic illustration of the spacial relationship of two probe assemblies and a roll in the grinding machine;

FIG. 4 is a diagrammatic cross section showing the basic organization of the two probe assemblies;

FIG. 5 is an end view, taken substantially along the line 5-5 

1. The method of initiating the turning of a nominally cylindrical workpiece which is supposed to be symmetrical about its lengthwise center, comprising the steps of placing the workpiece in a turning machine with the longitudinal axis of the workpiece aligned parallel with the longitudinal Z axis of movement of a tool, sensing the spacing between a reference line parallel to the Z axis and the surface of the workpiece near its left end, sensing the spacing between said reference line and the surface of the workpiece near its right end, signaling the polarity of the difference obtained by subtracting the left sensed spacing from the right sensed spacing utilizing the signaled polarity of said difference to move the tool to a longitudinal position opposite (a) the right end of the workpiece or (b) the left end of the workpiece depending upon whether such difference is positive or negative in polarity, respectively, then bringing the tool into contact with the work and initiating infeed and longitudinal passes of the tool to cut the workpiece, whereby the initial cutting pass of the tool results in removal of a progressively thinner layer from the surface of a workpiece, which is not symmetrical about its lengthwise center, during longitudinal movement of the tool.
 2. The method of initiating grinding passes on a nominally cylindrical roll in a grinding machine having a rotating grinding wheel movable along a Z axis substantially pArallel to the longitudinal axis of a roll in the machine and movable along an X axis normal to the Z axis, said machine having a probe assembly movable along the Z axis and including a probe extendable into contact with the roll and a transducer for producing a signal proportional in magnitude and agreeable in sense with the extent and sense of the displacement of the probe from a reference position, said method comprising the steps of grinding right and left gaging bands on the roll spaced equidistantly along the Z axis on opposite sides of the lengthwise center of the roll and such that the gaging band surfaces on that side of the roll closest to the wheel lie on a line parallel to the Z axis, bringing said probe first into contact with the left gaging band surface and second into contact with the right gaging band surface at points diametrically opposite wheel contact points on such surfaces, determining and signalling the polarity of the difference between said signal values when the probe is so in contact with the left and right gaging bands, moving the wheel while retracted free of the roll to one end or the other end of the roll surface in response to said signalled polarity being of one sign or the other, respectively, and infeeding the wheel and increment into the roll and then moving the wheel along the Z axis to execute a first grinding pass, the wheel bit thereby not becoming progressively deeper as the pass is executed.
 3. The method of initiating the grinding of a nominally cylindrical roll which is supposed to be symmetrical about its lengthwise center, comprising the steps of placing the roll in a grinding machine with that element of the roll surface adjacent to or contactable by the grinding wheel substantially parallel to the longitudinal Z axis of travel of the wheel, sensing and signalling the sign and magnitude of the difference between (a) the spacing between a reference line parallel to the axis and the surface of the roll at a first position lengthwise of the roll surface and (b) the spacing between said reference line and the surface of the roll at a second position spaced lengthwise from the first, utilizing the signaled difference to shift that end of the roll which is closest to said first lengthwise position in a direction transverse to the Z axis until the axis of the roll is parallel with the Z axis and the aforesaid element is not parallel with the Z axis, retracting the grinding wheel free of the roll surface moving it to (a) the end of the roll closest to said first position or (b) the end of the roll closest to said second position if said signaled difference is respectively (a) positive or (b) negative, and thereafter bringing the wheel into contact with the roll and initiating infeed and longitudinal passing of the grinding wheel, whereupon the first pass results in the wheel taking a progressively shallower rather than a progressive deeper bite from the roll surface as it moves longitudinally of the roll.
 4. The method of initiating the turning of a nominally cylindrical workpiece which may be initially and undesirably tapered in diameter, and thus larger in diameter near one end than near the other end where the diameters should be equal, comprising the steps of placing the workpiece in the left and right journaling supports of a turning machine, bringing the tool inwardly to a predetermined position along an X axis to cut a gaging band on the workpiece at a predetermined location to the right of the longitudinal center of the workpiece along the longitudinal Z axis of motion of the tool, bringing the tool inwardly to the same predetermined X axis position to cut a gaging band on the workpiece at a predetermined location to the left of the longitudinal center of the workpiece, said right and left predetermined locations being separated by a distance G and the latter being spaced by a distance A from the left support, the two gaging bands so cut having surfaces which lie along a straight line which is in Effect a tool-contact element on the workpiece and which is parallel to said Z axis, sensing and representing by the polarity and magnitude of an electrical signal the initial difference ( Delta ) between (a) the spacing between a Z axis reference line and the right gage band surface at an element diametrically opposed to the tool-contact element, and (b) the spacing between said Z axis reference line and the left gage band surface at the same element, moving the right journaling support in a direction transverse to the Z axis to pivot the workpiece about the left journaling support until the said signaled difference is changed to a value of Delta (G-A)/2G, thereby to make the workpiece axis parallel to the Z axis of the machine, moving the tool to a Z axis position opposite (a) the right end or (b) the left end of the workpiece in response to said electrical signal representing said difference ( Delta ) having respectively (a) a positive or (b) a negative polarity, bringing the tool into contact with the workpiece and cutting into the workpiece surface a predetermined distance, and then moving said tool respectively (a) to the left or (b) to the right along the Z axis to execute a first cutting pass in which the thickness of material removed from the workpiece diminishes as such movement progresses.
 5. In a turning machine for turning nominally cylindrical workpieces which are supposed to be symmetrical about their lengthwise centers, said machine having a tool movable along a Z axis substantially parallel to the axis of a workpiece placed therein and movable along an X axis normal to the Z axis, and having a probe assembly movable along a reference line parallel to the Z axis and including a probe extensible into contact with the workpiece surface together with a transducer for producing a signal proportional to the displacement of the probe tip from the reference surface; the improvement comprising in combination means for sensing and signaling the sign of the difference between the displacement of the probe tip when engaged with the roll at first and second locations spaced axially and equidistantly from the lengthwise center of the workpiece, means responsive to the signalled sign for moving the tool to one or the other end of the workpiece when the sign is of one or the other polarity, respectively, and control means for then infeeding the tool along the X axis a small increment into the workpiece and moving the tool along the Z axis to execute a cutting pass.
 6. In a grinding machine for grinding nominally cylindrical rolls which are supposed to be symmetrical about their lengthwise centers, said machine having a grinding wheel movable along a Z axis substantially parallel to the axis of a roll placed therein and movable along an X axis normal to the Z axis, the improvement comprising in combination having a probe assembly movable along a reference line parallel to the Z axis and lying diametrically opposite of the roll from the line of wheel contact with the latter, said probe assembly having a probe extensible to engage the roll surface and a transducer controlled by the probe to produce a signal indicative of the spacing between said reference line and the roll surface engaged by the probe, means responsive for determining and signalling the difference between the values of such signal when the probe is engaged respectively at first and second points on the roll surface spaced equidistantly along the Z axis to the left and the right of the lengthwise center of the roll, means responsive to the polarity of such signalling for moving the wheel to the left or right end of the roll surface when the polarity is negative or positive, respectively, and control means for moving the wheel into the roll and then along the Z axis to the opposite end of the roll to execute a grinding pass. 